Fuel cells, the main power suppliers of fuel cell systems, are devices that produce electric energy and water from a chemical reaction of oxygen in the air and hydrogen as fuel.
Hydrogen as the fuel of fuel cell systems is supplied to the anode of the fuel cell from a fuel tank and the air in the atmosphere is supplied directly to the cathode of a fuel cell stack by an air supplier.
The hydrogen supplied to the fuel cell stack is separated into hydrogen ions and electrons, the separated hydrogen ions flow to the cathode through an electrolyte membrane, and the oxygen supplied to the cathode produces water and generates electric energy by bonding with the electrons flowing into the cathode through an external conducting wire.
The fuel cell stack is formed by stacking in series unit cells generating voltage of around 1V in accordance with operation conditions, and when even one of the cells fails to achieve its normal performance, it causes output reduction of the entire stack. Accordingly, it is determined whether there is a problem by measuring the voltage of the unit cells while the fuel cell stack operates, with a voltage measuring device in contact with a portion of a bipolar plate.
The voltage measuring device includes sensing units that measure voltage, and a terminal guide is disposed between the sensing units, and thus prevents a short-circuit between the sensing units, and allows the terminal of the bipolar plate and the sensing units to be uniformly inserted when the voltage measuring device is combined with the bipolar plate.
Recently, however, the opening direction of fuel cells is set in a way of reducing the cell pitch and the thickness of the material for the bipolar plate in order to improve the power density of stacks.
Although the thickness of the terminal guide in the voltage measuring device is supposed to be reduced as much as the cell pitch is reduced, at present, there is a technical limitation on reducing the thickness of the terminal guide.
Further, the bending resistance rapidly decreases with the reduction of the thickness of the bipolar plate, so it is more difficult to keep the gap between the terminals of the bipolar plate constant and the terminals of the bipolar plate are damaged by external force when the voltage measuring device is combined.
Therefore, there is a need for a technology that can keep the gap between the terminals of a bipolar plate constant even if the cell pitch and the thickness of the bipolar plate are decreased and that prevents the terminals of the bipolar plate from easily deforming due to external force or shock when a voltage measuring device is combined.
The description provided above as a related art of the present inventive concept is just for helping in understanding the background of the present inventive concept and should not be construed as being included in the related art known by those skilled in the art.